In this work, we give the first $\tilde{O}(\log n)$-round secure computation protocol in the plain model that achieves angel-based composable security in the concurrent setting, under standard assumptions. We do so by constructing the first $\tilde{O}(\log n)$-round CCA-secure commitment protocol. Our CCA-secure commitment protocol is secure based on the minimal assumption that one-way functions exist.
A central tool in obtaining our result is a new \emph{robust concurrent extraction lemma} that we introduce and prove, based on the minimal assumptions that one-way functions exist. This robust concurrent extraction lemma shows how to build concurrent extraction procedures that work even in the context of an ``external'' protocol that cannot be rewound by the extractor. We believe this lemma can be used to simplify many existing works on concurrent security, and is of independent interest. In fact, our lemma when used in conjunction with the concurrent-simulation schedule of Pass and Venkitasubramaniam (TCC'08), also yields a constant round construction based additionally on the existence of quasi-polynomial time (\pqt) secure one-way functions.
Category / Keywords: foundations / Concurrent Extraction, Composable Security Publication Info: Manuscript Date: received 15 Nov 2012, last revised 16 Feb 2013 Contact author: omkant at cs utexas edu Available format(s): PDF | BibTeX Citation Note: This is a merger of two works, by following group of authors: (1) Huijia Lin and Rafael Pass, and (2) Vipul Goyal, Omkant Pandey, and Amit Sahai Version: 20130217:041721 (All versions of this report) Discussion forum: Show discussion | Start new discussion